1. Field of the Invention
The invention relates to a non-contact transfer hand.
2. Description of Related Art
A technique regarding a non-contact transfer hand is disclosed in Japanese Patent Application Publication No. 2009-032744 (JP 2009-032744 A). A Bernoulli chuck (a non-contact transfer hand) described in JP 2009-032744 has a configuration in which a grip unit is coupled to a disc-shaped suction holding plate. In this suction holding plate, a suction surface for holding a workpiece has four air discharge grooves that are located on an outer peripheral side of the suction holding plate. An outer end and a suction surface side of each of the air discharge grooves are opened. In addition, a compressed air supply passage and a distribution flow passage are bored in the suction holding plate. The compressed air supply passage is communicated with a discharge pump. The distribution flow passage communicates between the compressed air supply passage and the four air discharge grooves. The air supplied from the grip unit flows through the compressed air supply passage and the distribution flow passage that are formed in the suction holding plate, and is discharged from the air discharge grooves. The compressed air that is discharged from the air discharge groove draws peripheral air by an ejector effect and thus generates a suction force to suck the workpiece over the suction surface. In addition, since the compressed air flows through the air discharge groove at a high speed, negative pressure is generated around the air discharge groove by Bernoulli effect. In this way, the workpiece is sucked over the suction surface.
In the case where the compressed air supply passage and the distribution flow passage are formed in the above-described non-contact transfer hand in the related art, a long narrow hole has to be formed in the suction holding plate by drilling. In order to form the long narrow hole by drilling, a drill needs to have a small diameter. However, reduction in diameter of the drill is not preferable when breaking or bending of the drill during a process is taken into consideration. As a result, it is difficult to form the hole with a small diameter. For this reason, in the related art, it is difficult to reduce a thickness of the suction holding plate.